referncing document should not be changed

Dear SAP Gurus,

I have a scenario and it is for example that if sales order is created with reference to the quotation so quotation should not be changed....and the sales order should have the same material which is copied from the quotation and we should not enter other material in the sales order which is not in the quotation and same thing for the delivery.......so can anybuddy tell me that from where we can control this thing from the standard system......